After FOX Searchlight's Amelia spectacularly flamed out last October, the studio tries again to grab awards-season honors with another biopic starring and executive-produced by Hilary Swank. Gone is the Kansas-patrician enunciation and smartly tailored Depression-era trousers; as Conviction's Betty Anne Waters, a Massachusetts high school dropout and single mom who put herself through law school to exonerate her brother, Kenny, wrongfully imprisoned for murder, Swank dutifully returns to the working class, the caste of her past Oscar glory.

Director Tony Goldwyn and writer Pamela Gray, previous collaborators on 1999's A Walk on the Moon, skip over most of the specifics of Waters' extraordinary accomplishment to insert superfluous heart-tugging childhood flashbacks. The pint-size Betty Anne and Kenny (Bailee Madison, the adorable dumpling from last year's Brothers, and Tobias Campbell), two of nine children sired by seven different fathers, are trotted out once too often to establish the origins of the unbreakable sibling bond. Mom Waters (Karen Young), distracted by man problems, pays no attention to the tykes, whose playtime includes breaking and entering the trailer home of a nearby German woman. As foster-home separation looms, tiny limbs flail, and brother and sister promise to always be there for each other.

The meagerly furnished residence that was once Betty Anne and Kenny's romper room becomes, in 1980, a gory crime site; neighbor Katharina Brow is found — in the words of the crooked lady cop (Melissa Leo) who arrests adult hell raiser Kenny (Sam Rockwell) for the murder — "stabbed 30 times and her head bashed in until her brains fell out." The perjury of two of Kenny's ex-girlfriends (Clea DuVall and Juliette Lewis, reveling in snaggle-toothed white-trash high camp) sends him, in 1983, to the clink for life — and Rockwell, usually a loose, pleasingly unpredictable presence onscreen, to actors' detention camp, forced into the standard staginess of prison-visit scenes with Swank.

"I will never accept it!" Betty Anne declares, devoting the next eighteen years to proving her brother's innocence. Instead of looking closely at Waters' enormous sacrifices and the toll of her commitment — perfunctorily depicted as falling asleep on her keyboard while writing her torts paper and remaining in her Cape Cod chip-covered bed for several days after her sons decide they'd rather live with their dad — Conviction presents its heroine as a construct of uncomplicated altruism and determination. She is, in other words, the perfect role for Swank, whose robotic eagerness to please, to perfect regional accents, to play up big emotions and to collect statuettes has made her the Stepford Wife of the fall-movie season.

Swank's inauthentic pantomime of blue-collar grit becomes even more glaring in her scenes with supporting player Minnie Driver as Abra, a classmate of Betty Anne's at the Roger Williams University School of Law. Spotting Betty Anne working behind the bar one night, Abra aggressively insists they become friends; Driver conveys her character's weirdly touching mix of pushiness and loyalty with a relaxed sense of humor. But as the script calls for the two women to work together to clear Kenny — a project that begins at the exact moment in 1992 when Betty Anne first hears the term "DNA test" — Driver, like Rockwell, gets sacrificed to the lead's bid for Indefatigable Heroine Greatness.

In all fairness, Swank's unsubtle performance is often an extension of the bluntly dumb lines she and other cast members must deliver. Around the time that a dazed Peter Gallagher shows up as Barry Scheck to leave stern phone messages for then-D.A. Martha Coakley, who ignored the DNA evidence, the failures of the U.S. justice system are expressed as fridge-magnet maxim: "People don't like to admit when they've been wrong."

Similarly, Conviction, its end title cards informing viewers of Betty Anne's current activities, refuses to acknowledge the unbearable tragedy of Kenny Waters: Finally released from prison in March 2001, he died six months later after he fractured his skull in a fall. The deliberate withholding of this information doesn't make Swank's plastic performance any nobler — it only patronizes the amazing real-life woman she plays and the complexities of her story.